GLACERS OF THE WASHNGTON CASCADE AND OLYMPC MOUNTANS 669 GLACERS OF THE WASHNGTON CASCADE AND OLYMPC MOUNTANS; THER PRESENT ACTVTY AND TS RELATON TO LOCAL CLMATC TRENDS By RCHARD C. HUBLEY (University of Washington, Seattle) ABSTRACT. Between '953 and 1955. 73 glaciers in the Olympic and Cascade Mountains of Washington State have been investigated to determine their present activity. 50 of these glaciers are now advancing at rates from 3 to 100m. or more per annum. Of the remaining 23. 22 glaciers either demonstrate clear evidence of increasing thickness, or have remained so heavily snow-covered at the end of the ablation season that it has not been possible to locate their limits. The present glacier growth. which appears to have started about 12 years ago. represents a radical change from conditions during the previous 20 years when glaciers of the Olympics and Cascades without exception were shrinking rapidly. An analysis of local climatic data demonstrates a present trend toward a cooler, wetter climate in western Washington. The ten year running mean annual temperature at Tatoosh sland off the Washington coast has decreased approximately 0'8 0 C. from the period '934-'943 to the period 1945-1954. n the same interval of time the ten year running mean annual precipitation at Tatoosh has increased about 38 em., and during the last decade has reached its highest value since the period 1898-1907. ZUSAMMENFASSUNG. Zwischen '953 und '955 sind 73 Gletscher in den Olympic und Cascade Mountains des Staates Washington untersucht worden. um ihre gegenwlirtige Tlitigkeit festzustellen. Fiinfzig dieser Gletscher bewegen sich jetzt mit einer Geschwindigkeit von 3 bis JOO m. oder mehr pro Jahr vorwlirts. Von den ubrigen 23 Gletschern zeigen 22 entweder ganz klar eine zunehmende Dichte auf, oder sie sind am Ende der Ablationssaison so tief mit Schnee bedeckt geblieben, dass ihre Grenzen nicht ausfindig gemacht werden konnten. Das gegenwlirtige Anwachsen der Gletscher, das vor etwa 12 Jahren begonnen zu haben scheint, entspricht einem radikalen Wandel der Zustlinde der vorherigen 20 Jahre, in denen die Gletscher der Olympic und Cascade l\10untains ohne Ausnahme in schnellem Ruckgang begriffen waren. Eine Analyse der lokalen klimatischen Verhliltnisse llisst eine gegenwlirtige Neigung zu einem kiihleren, feuchteren Klima im Westen Washingtons erkennen. Die zehn Jahre laufende Durchschnittstemperatur auf der nsel Tatoosh gerade abseits der Kiiste von Washington hat seit der Periode '934-1943 bis zur Periode '945-'954 um ungeflihr 0,8 0 C. abgenommen. n dem gleichen Zeitabschnitt hat sich der zehn Jahre laufende Durchschnittsniederschlag auf Tatoosh um 38 cm erhoht und hat jm letzten Jahrzehnt seinen Hochstwert seit der Periode 1898-1907 erreicht.. NTRODUCTON Approximately ninety per cent of the total glacierized area in the continental United States is located in the Cascade and Olympic Mountains of Washington State in the north-west corner of the country. Glacier studies in the Cascades and Olympics have been very few and, in fact, the most heavily glacierized sections of the Northern Cascade ranges remain largely unexplored. n the last few years, interest in glaciers of this region has been aroused by discovery of gro\vth of Nisqually Glacier on Mt. Rainier, and advance of Coleman Glacier on Mt. Baker!, 2. The purpose of this paper is to present preliminary results of two related investigations started in 1953: () To determine whether increased activity on Nisqually and Coleman Glaciers was an isolated, anomalous phenomenon, or was indicative of a general reversal in glacier activity from the widespread shrinkage of glaciers in the Olympics and Cascades which has been the pattern for the past several decades. (2) To analyze local meteorological data for any indications of recent climatic trends which might relate to the present glacier activity in the Olympic and Cascade Mountains. The large number of glaciers in the Olympic and Cascade ranges precludes the possibility of investigating each glacier individually. For this reason, small but diversified groups of glaciers representative of the high Cascade volcanoes, the Northern Cascade ranges, and the Olympic Mountains were selected for observation.. GENERAL DESCRPTON OF GLACERS AND THER PRESENT ACTVTY 1. High Cascade Volcanoes.-Glaciers of the high volcanoes oil< cover an aggregate area estimated at 190 km.2 n general, the glaciers are very active, steep gradient valley tongues originating from high neve fields at elevations from 2700 to 4200 m. above sea level. These glaciers appear These include Mt. Baker, 3287 m.; Glacier Peak, 32 m.; Mt. Rainier. 4394 m.; and Mt. Adams. 3754 m. See Fig., p. 670'
670 JOURNAL OF GLACOLOGY to be particularly sensitive to meteorological conditions during the warm part of the year. With their steep slopes and elevated positions above surrounding topography, all but the north-facing glaciers are well exposed to solar radiation. During a particularly wet year, however, the higher parts of these glaciers continue to receive snow accumulation throughout the summer months. Since 1953, at least five glaciers on Mt. Rainier and six on Mt. Baker have been visited by various observers. Two glaciers on Mt. Rainier, and four on Mt. Baker have been found advancing. Although their termini are not yet advancing, the remaining three glaciers on Mt. Rainier and two on Mt. Baker all demonstrate growth through such qualitatively observable evidence as expansion of icefalls, and the rise of ice surface levels relative to lateral bedrock faces. n September 1955, the nine largest glaciers on Glacier Peak were aerially photographed, and the positions of their termini compared with termini positions shown in 1950 aerial photographs taken of Glacier Peak by the U.S. Geological Survey. Eight of the nine glaciers are advancing. The ninth glacier was so deeply buried under firn in both the 1950 and 1955 photographs that it Fig.. Part of Washington State showingthe locations of the high volcanoes, Northern Cascades and Olympic Mountains 01011. Roinier am Adorns was not possible to locate the positions of the terminus during those years. t was possible to locate four of the positions of the termini with sufficient accuracy in both the 1950 and 1955 photographs to compute their advances. The least of the four showed 180 m. advance for the five year period, while the greatest, measured for the Chocolate Glacier (Figs. 2 and 3, p. 678) was 400 m. 2. Northern Cascade Ranges.-Northern Cascade glaciers cover an aggregate area conservatively estimated at 320 km.2 This group includes many hundreds of small cirque and hanging glaciers, and a few very large cirque glaciers and ice aprons, some with valley tongues (Figs. 4 and 5, p. 679)' The glaciers originate at elevations from 1950 to 2700 m., and vary considerably in steepness and rates of movement. During the past decades of retreat, many glaciers in these mountains disappeared entirely, or became totally stagnant. With the onset of a period of glacier growth, therefore, many of these glaciers must first build up an appreciable thickness of ice before advance can occur. n September 1955, aerial photographs were taken of 48 glaciers in the Northern Cascades. Most of the 48 glaciers appear in aerial photographs taken in 1950 by the U.S. Geological Survey,
GLACERS OF THE WASHNGTON CASCADE AND OLYMPC MOUNTANS 671 and the remainder were photographed from the ground in 1953: Comparison of the earlier and later photographs show that 33 of the 48 glaciers are advancing. Of the remaining S glaciers, one terminates on a steep slope, and is avalanching into the valley below; eight glaciers are nearly or completely covered with firn so that the positions of their termini cannot be determined; and six are as yet stagnant. t was possible to fix the distances over which four glacier termini advanced in the past five years. Values are given in Table. TABLE Glacier Length in 9So (Km.) Area in 9So (Km.") Advance between 9SO and 9SS (Meters) Northern Cascades Ladder Creek nspiration N.E. side of Eldorado Peak (unnamed) Boston.. Glacier Peak Kennedy West sde of peak (unnamed). ~ Tower........ Chocolate 1'5 4'8 1 8 6'7 width 2'4 max. length 3'0 3'0 3'3 4'7 60 180 235 560 180 200 220 400 The values given here are believed to be correct within ten per cent. The amount of advance varies considerably from one part of the 6'7 km. wide front to another. The tabulated value is the maximum. 3. Olympic Mountains.-Although the glacierized area in the Olympic Mountains is very small (estimated 65 km.2), the Olympic glaciers are in some ways the most unique apd interesting in the United States. Unlike the Cascades, the Olympic ranges do not form an elongated chain of mountains; rather they are massed in the center of a peninsula with the Pacific Ocean to the west, the Straits of Juan de Fuca to the north, Puget Sound and its lowlands to the east, and a low, broad river valley to the south (Fig. ). Winters in the Olympics are mild but extremely wet. Summers are very cool and generally damp. n this highly maritime environment, glaciers are formed at lower elevations than elsewhere in the Northern Hemisphere at similar latitudes. The largest Olympic glaciers head at elevations from 1800 to 2250 m. and have low gradient, dynamically active tongues terminating at elevations from 1000 to 1350 m. There are also many cirque glaciers in the Olympics, several of which lie entirely below 1500 m. 3. Because of their low altitudes, these glaciers are particularly sensitive to wintertime temperature fluctuations. During exceptionally warm winters, the atmospheric freezing level frequently rises above the glaciers so that precipitation, though it be plentiful, falls as rain and the glaciers suffer from lack of accumulation. n the last year, five glaciers in the Olympics have been observed for activity. Three of these are advancing, though at very low rates, and one shows positive evidence of considerable increase in ice thickness up-glacier from its terminus. nsufficient data are available on the fifth glacier to draw any conclusions as to its activity. Many of the small cirque glaciers in the Olympics, as well as in the Cascades, have remained completely snow covered throughout the past three ablation seasons.. RECENT CLMATC TRENDS N WESTERN WASHNGTON AS RELATED TO GLACER GROWTH The investigation of climatic trends is difficult in this region because few climatological stations have records over any appreciable time period. Furthermore, most station sites have been changed during the stations' periods of record. For the present work, one station was found to have a sufficiently long record unaffected by changes in station site for a reliable analysis of temperature and precipitation trends. This station is Tatoosh sland, located off the north-west coast of Washington near the mouth of the Straits of Juan de Fuca.
672 JOURNAL OF GLACOLOGY n Fig. 6 (p. 673) are shown the running ten year mean annual temperatures for Tatoosh sland from the beginning of the temperature record. n Fig. 7 are shown the running ten year mean annual precipitation amounts for Tatoosh from the beginning of the precipitation record. t is not possible to relate quantitatively the observed glacier growth to the present precipitation and temperature trends at Tatoosh as glacier growth or shrinkage.has no simple relationship with these two factors. Changes in wind speeds, prevailing wind directions, degree of cloudiness and other factors are also exceedingly important in causing changes in glacier regime. Qualitatively the present period of glacier growth corresponds to a period of decreasing temperatures and increasing precipitation in the Tatoosh meteorological record. This trend toward a cooler, wetter climate first appears in the Tatoosh records about 1943. The first sign of glacier growth was found by Arthur Johnson of the U.S. Geological Survey in 1944 on Nisqually Glacier4 Upper air temperatures measured by radiosonde and airplane flights were also used for analysis of climatic conditions associated with the present glacier activity. n Table are given the number of months out of each year for the past two decades during which the free air tem~ perature at 1500 m. over Tatoosh sland averaged 0 C. or lower, and during which the free air temperature at 1500 m. averaged 10 C. or higher. t is assumed that the pattern of monthly TABLE No. of months avo No. of months avo No. of months avo No. of months avo Year temp. at or below temp. at or above Year temp. at or below temp. at or above 0 0 C. 10 0 C. 0 0 C. 10 0 C. 1935 3 1945 5 2 1936 3 2 1946 5 1 1937 3 3 1947 1 1 1938 2 4 1948 5 1939 2 3 1949 4 1 194 1 3 1950 5 3 1941 2 2 1951 4 4 1942 3 3 1952 5 1943 Missing Missing 1953 5 4 1 1944 4 3 1954 3 Above data calculated from free air temperatures 1500 meters above Tatoosh sland. temperatures itt corresponding elevations in the mountains is simil~r to that shown in the free air data taken over Tatoosh. On this basis, the data indicate that: (a) the length of the ablation season has decreased; (b) monthly mean temperatures during the ablation season have decreased; and (c) the number of months during which snow accumulates on the glaciers has increased. The latter factor suggests that during the past several years the increase in snow accumulation on the glaciers has been greater than is indicated by the increase in annual precipitation alone. An attempt was made to obtain a specific correlation between meteorological data from Tatoosh and annual rate of retreat of the Blue Glacier in the Olympic National Park, as measured by the National Park Service. f thy terminal ice of a glacier is stagnant, i.e., transport of ice by glacier motion is zero at. the terminus, the rate of retreat of the terminus wi be a function only of ice thickness and rate of ice ablation at the terminus. f the thickness of ice at the te~minus does not vary greatly from year to year, the rate of retreat can provide a signific~t record of changes in the net energy received from the sun and atmosphere at the terminus during the ablation season. Until 1954, the Blue Glacier had a retreating snout which fulfilled to some extent the above conditions. Fig. 8 (p. 673) demonstrates the relation between rate of retreat of the Blue Glacier snout and meteorological data from Tatoosh sland. Located in a deep canyon, the terminal region of this glacier is well protected from regional winds. Melting at the terminus is produced primarily by radiation and by turbulent transfer of heat from a well-defined, local down-glacier wind. ntensities of both the down-glacier wind and back radiation from atmospheric water vapor and clouds
GLACERS OF THE WASaNGTON CASCADE AND OLYMPC MOUNTANS 673 depend on difference between glacier temperature and free air temperature. There is, therefore, a basis to expect some correlation between melting at the terminus and free air temperature. The solid line in Fig. 8 shows annual rate of retreat of the Blue Glacier terminus from 1938 to 1954 in meters per year. The dashed line shows excess of free air temperature above freezing in degreemonths at 1500 m. A direct correlation between rate of retreat and temperature excess is apparent up to the year 1947. Here the correlation breaks down. t is likely that after this time, increase in winter accumulation of snow over the terminal ice probably shortened considerably the period of 10..s ci w 9.5 c! w '" ::> - 0< '"w Q,,. ~ 9 200 190 1907 1917 1927 1937 J947 1957 180 /887 1897 1907 --' 1951 60 100, 90,, 80, 70,, 60 \ \ \ \ /\ 1,, \ \ ' \ ' \, \ \1 \ ' \.,' " \, - -------- --'" 50 40 a: w 0. Fig. 6 (above left). Running ten year mean annual temperatures at Tatoosh sland, Washington. Along the ordinate is plotted the last year of each ten year mean Fig. 7 (above right). Running ten year mean annual precipitation values at Tatoosh sland, Washington. Along the ordinate is plotted the last year of each ten year mean Fig. 8 (below). Annual rate of retreat of Blue Glacier as related to temperature. Solid line, annual retreat in meters. Dashed line, annual temperature excess over freezing in degreemonths 20 0: "' w - W ~ 20 '0 10 193940 41 42 43 44 45 46 47 48 49 50 51 52 5354 43
674 JOUtNAL OF GLACOLOGY time each year during which the terminal ice was exposed to melting. An additional influence may well be change in the physiographic environment of the snout as it' retreated up-valley, for the physiographic environment exerts a strong influence on the energy transfer at the ice surface. Changes in thickness of the terminal ice might aiso have been a factor. Had simultaneous measurements been available from other stagnant termini in the vicinity of the Blue Glacier, comparison. of data might have allowed separation of fluctuations in retreat of termini related to general meteorological conditions from those resulting from local physiographic influences. Since 1954 the terminus of the Blue Glacier has advanced. The effect of this advance on further analysis of annual rates of change in position of the terminus will be greatly to complicate the situati9n. t will now be necessary to consider the amount of ice delivered each year to the terminus by flow from the upper portions of the glacier-a factor 'not necessarily related to meteorological conditions in a specific year. V. CONCLUSONS Observations have clearly demonstrated that a period of general growth of glaciers in the Olympic and Cascade Mountains in Washington State is in progress. Analysis of climatic data from Tatoosh sland indicates that in the most general terms, the glacier growth is associated with a present trend which began about twelve years ago toward a cooler, wetter climate. The effect on glaciers of this trend has been to increase the length of the annual accumulation season and the rate of accumulation. Conversely, the length of the ablation season has decreased as have air temperatures during the ablation season. The extent of the area along the Pacific Coast outside of Washington State within which general growth of glaciers is occurring is not definitely known. Positive evidence of glacier growth 'has been found to the south on Mount Shasta in northern California. Analysis of meteorological data from Juneau, Alaska, approximately ten degrees of latitude north of Washington State, has not shown any pronounced trend toward a cooling of the climate such as that found in the Tatoosh records. Firn limits in the Juneau ce Field, however, have been observed to remain at unusually low elevations on the glaciers during the past two ablation seasons. Further reconnaissance surveys of glacier activity are needed, particularly in the Coast Range of British Columbia. n the meantime, groundwork has been laid during the 1955 summer field season for detailed, quantitative measurements of the regimen of the Blue Glacier in the Olympic Mountains. These studies include annual budget measurements and micrometeorologi.cal and glacier kinematics studies. Continuation of this program should lead to a much better understanding of what is happening to the glaciers in this area at present. Results of detailed studies on the Blue Glacier'in 1955 will appear in a later paper. V. ACKNOWLEDGEMENTS This work has been made possible by a grant from Agnes Anderson Research Funds, University of Washington. Cooperation of the Olympic National Park Service on phases of this investigation carried out in the Olympic Mountains is gratefully acknowledged. iv/s. received October 1955 REFERENCES. Harrison, A. E. Fluctuations of the Nisqually Glacier, Mt. Rainier, Washington, since 1750. Journal of Glaciology, Vol. 2, No. 19, 1956, p. 675. 2. Bengtson, K. B. Activity of the Coleman Glacier, Mt. Baker, Washington, U.S.A., 1949-1955 [in/ress). 3. Earlier descriptions of the glaciers of the Olympics have been published in Matthes, F. E., an others. Report of Committee on Glaciers, 1945. Transactions of the American Geophysical Union, Vol. 27, No.2, 1946, and in Danner W. H. Geology of Olympic National Park. Seattle, University of Washington Ptess, 1955. ' ' 4. Harrison, A. E., op. cit.
Fig. 4. (See p. 670.) Chikamon Glacier, Northern Cascades, in September 955. The ice apron has advanced appreciably since the glacier teas last visited and photographed in 953. Activity on the icefall in the valley tongue has increased, however the terminus of the tongue is as yet stagnant Fig. 5. (See p. 670.) Boston Glacier, Northern Cascades, in September [955. The tzeo visible tongues, One to the right and one to the left of the picture center have formed completely since 950. 11aximum advance of the glacier fronl 1('as 560 m. betn'een [950 and [955
Fig. 2. (See p. 675.) Vie'Vof Mt. Rainier and the /\lisqllally Glacier from Nisqllally Vista, a point 011 the rim of the conyoll jllst above the termilllls of the glacier Figs, Ja (top right), Jb (bottom left) Old JC (bottom right). (See p. 676.) Telephoto t:ielcsof the ice,cave on the Nisqllally Glacier ill 1951, 953 alld 955 respectit:ely. The 'rave had jllst reached the la"a-capped rock ill the lon'er right earlier ill Fig. Ja